LA County COVID-19 Infections Far Exceed Number of Confirmed Cases

Findings from first round of ongoing antibody blood testing of county residents

TUESDAY, April 21, 2020 (HealthDay News) — An early analysis of antibody testing from Los Angeles County reveals a COVID-19 infection rate that is up to 55 times the number of confirmed COVID-19 cases.

The Los Angeles County population totals more than 10 million. As the research team noted, by early April, there were 7,994 confirmed cases of COVID-19 reported in the county, including 600 COVID-19 deaths. But new findings from the first round of ongoing antibody blood testing of county residents showed that about 4.1 percent of adults had antibodies to COVID-19. Adjusting for any statistical margin of error, that number suggests that 2.8 to 5.6 percent of the county’s adults have antibodies to COVID-19, which translates to 221,000 to 442,000 adults in Los Angeles County having already had the infection.

That estimate is 28 to 55 times higher than the number of confirmed cases of COVID-19 reported to the county by the time of the study in early April, said researchers from the University of Southern California (USC) and the Los Angeles County Department of Public Health.

“We haven’t known the true extent of COVID-19 infections in our community because we have only tested people with symptoms, and the availability of tests has been limited,” lead investigator Neeraj Sood, Ph.D., professor of public policy and senior fellow at the Center for Health Policy and Economics at USC, explained in a university news release. Now that the true, and much wider, penetration of COVID-19 within the general public is known, “we might have to recalibrate disease prediction models and rethink public health strategies,” Sood added.